1. Field of the Invention
The present invention relates to a semiconductor device, and more particularly, to a semiconductor device that can restrict fluctuations of the ON current of a complementary field effect transistor.
2. Description of Related Art
In semiconductor devices such as a DRAM (Dynamic Random Access Memory), complementary field effect transistors such as a CMOS (Complementary Metal Oxide Semiconductor) are often used for peripheral circuits (see Japanese Patent Application Laid-Open No. 2008-059680, for example).
In recent years, miniaturization and lowering of voltage are being rapidly achieved in the development of semiconductor devices. As the miniaturization and the lowering of voltage progress, the variations among the threshold voltages of the transistors forming complementary field effect transistors become larger, and the fluctuation of the ON current becomes larger accordingly. Also, due to the lowering of the threshold voltage, the OFF current of the entire chip cannot be ignored, and the fluctuations of the OFF current adversely affect the standby current.